public class D11 {
    public static void main(String[] args) {
        // common class overview
        // Number & Math
        Integer x = 5;
        System.out.println("Sin 90 " + Math.sin(Math.PI/ 2));
        System.out.println("Cos x " + Math.cos(x));
        System.out.println("Tan ? " + Math.tan(Integer.MAX_VALUE));
        System.out.println("Atan ? " + Math.atan(Integer.MIN_VALUE));

        double[] dnums = new double[] {1.0, 2.0, 3.0, 4.0};
        for (double d: dnums) {
            System.out.println(d);
            System.out.println(Math.floor(d));
            System.out.println(Math.round(d));
        }

        // Character
        char ch = 'a';
        char uniChar = '\u039A';
        char[] chArray = {'a', 'b'};
        System.out.println(ch );
        System.out.println(uniChar);
        for (char c: chArray) {
            System.out.println(c);
        }

        Character ref_ch = ch;
        if (Character.isLetter(ref_ch)) {
            System.out.println("OK, it is a letter");
        } else if (Character.isLowerCase(ref_ch)) {
            System.out.println("Ok, it is lowercase");
        } else {
            System.out.println("whatever");
            
            ref_ch.toString();
        }

        // String

        // StringBuffer

        


    }
}
